I am having difficulty deciding on where to place my speakers. The wall I am putting the screen on is only 92" wide and the screen is 88" wide. So obviously I can't put the L/R speakers to the side of the screen.

The ceiling is 9' and I was planning on putting the center of the screen at 4.5'. The screen is 49.8" tall, so this would put the bottom of the screen at 29.1" and the top at 78.9".

I've read that LCR speakers should ideally all be at the same height, so mine will either have to all go above or below the screen.

There doesn't seem to be a consensus on which option is better. As of right now I am leaning towards placing all 3 LCR speakers above the screen but would like to hear some feedback.

There will only be one row of seats that can be moved from 10' to 13' from the screen.

Don't believe everything you read. They are three discrete speakers playing three discrete sources, so while they should have very similar, if not identical, frequency response, they need not be at the same level. What comes from the center will seem to be coming from the center of the screen, whether it's above or below the screen, because your eyes says so, and visual directional cues over-ride audio directional cues. I have my L/R up high, aimed downward, and my center below the screen, because there's no room for it above the screen. No issues at all.
Depending on the angle of the seats you might put the screen higher. I sit in a recliner, my screen center is 6 feet above the floor, the top 6 inches from the ceiling.

Don't believe everything you read. They are three discrete speakers playing three discrete sources, so while they should have very similar, if not identical, frequency response, they need not be at the same level. What comes from the center will seem to be coming from the center of the screen, whether it's above or below the screen, because your eyes says so, and visual directional cues over-ride audio directional cues. I have my L/R up high, aimed downward, and my center below the screen, because there's no room for it above the screen. No issues at all.
Depending on the angle of the seats you might put the screen higher. I sit in a recliner, my screen center is 6 feet above the floor, the top 6 inches from the ceiling.

The guy that sold me the speakers suggested I do the same as you, LR above screen and center below. Good to know someone has actually tried this.

I will probably play around with different locations before I cut the holes in the wall.

Don't believe everything you read. They are three discrete speakers playing three discrete sources, so while they should have very similar, if not identical, frequency response, they need not be at the same level. What comes from the center will seem to be coming from the center of the screen, whether it's above or below the screen, because your eyes says so, and visual directional cues over-ride audio directional cues. I have my L/R up high, aimed downward, and my center below the screen, because there's no room for it above the screen. No issues at all.

This is great advice if all the speakers have perfect off-axis vertical response.

If, like all speakers in the real world, the off-axis vertical response varies from the on-axis response; then this will make the center out of tembre' (possibly to downright bad). You could solve the problem by angling the center speaker up; but that's going to create a "sweet spot" that's on-axis surrounded by off-axis areas.

Some speakers have good off-axis vertical dispersion, but others do not. I certainly would not reccommend something like an ML planar speaker for such use.

In short: I think the advice can work for some speakers and some setups; but will be problems with others.

Given how close together your speaker are: I wonder if a center channel is even appropriate. Of course, some people will tell you that you need a speaker in the center to hear sound in the center, but these same people will tell you that a center on the floor will make sound in the center of the wall; so perhaps that claim deserves a grain of salt.

I would do all speakers below the screen. The reason is seamless panning for the sound field. I've tried the center low and L/R high and didn't like the result. Even though they are in-walls, I suggest temporarily placing them at the possible locations and listening for yourself.

I ended up putting all 3 front speakers above the screen. I used the Audyssey setup mic that came with the Denon X1000 and the results are great. The sound seems to come from the screen, not above. I couldn't be more pleased.